Silicon substrates are used in the fabrication of semiconductors and solar cells. During such fabrication, the substrates are subjected to a multi-step manufacturing process that may involve a plurality of machines and a plurality of stations. Thus, the substrates need to be transported from one machine/station to another machine/station one or more times.
The transport of the substrates typically employs apparatuses called end effectors. A typical end effector may be a flat platform having a hand-like or claw-like appearance defined by a base unit with a plurality of flat fingers or tines extending therefrom. The fingers may be adapted to support a substrate in a horizontal orientation. During operation, the end effector may typically be moved linearly (e.g., forward and backward) as well as rotationally all in the same plane (e.g., x-y axis). The end effector may also be moved in a third direction along a z-axis to provide a full range of motion. It is generally desirable for end effectors to be formed of materials that are lightweight, that are stiff, and that do not produce contaminants (i.e., particulate matter) during use. It is also generally desirable for end effectors to have working surfaces (i.e., surfaces that engage substrates) that are very flat, hard, and easy to clean. Still further, it is generally desirable for end effectors to be very thin to facilitate insertion between silicon substrates that are stored in a stacked arrangement in close vertical proximity to one another, such as in a front opening unified pod (FOUP) or other storage medium.
It is common for end effectors to be provided with sensors and/or other components that facilitate the loading, unloading, positioning, and/or secure transport of silicon substrates. For example, an end effector may be provided with a photoelectric sensor, such as a through beam sensor, for detecting the presence or absence of substrates in a FOUP or other storage medium from which substrates can be collected for subsequent transport and processing. It is also common for end effectors to be provided with electrostatic chucks (“e-chucks”) that are capable of producing electrostatic forces for securely clamping substrates to an end effector during transport and/or processing.
Although sensors and components such as those described above may confer numerous advantages and benefits, they are also associated with a number of drawbacks. For example, the provision of such sensors and components, which are typically mounted on the top and/or bottom surfaces of an end effector, can increase the overall profile and thickness of an end effector. Furthermore, such sensors and components, including associated wiring, connectors, fasteners, etc., create irregularities on the otherwise flat surfaces of an end effector. Such surface irregularities can complicate, and therefore prolong, the cleaning of an end effector, thereby creating undesirable delays during manufacturing processes.
In view of the foregoing, it would be advantageous to provide an end effector having sensors and/or other components that aid in the loading, unloading, positioning, and/or secure transport of substrates, wherein such end effector has substantially flat, easy-to-clean surfaces. It would further be advantageous to provide such an end effector having a very thin profile.